Chlorinated paraffin waxes, particularly higher molecular weight solid or liquid higher chlorinated paraffins in the C.sub.10 to C.sub.30 range have been widely used for over fifty years in metalworking uses, particularly as lubricant additives in drawing oils, extrusion oils and soluble oils, and particularly for extreme pressure applications. The largest volume is in drawing oils where chlorinated waxes are used almost exclusively, mainly in mineral oils. In extrusion oils, the additives usually include phosphorous and sulfur compounds due to the severity of operations. In soluble oils the chlorinated waxes are usually used in combination with fats or lard oils.
In 1977, twenty percent (40,000 tons) of the free-world production of liquid chlorinated paraffins was used in oil applications. However, in recent years, concern has arisen regarding toxicity and possible carcinogenicity of chlorinated paraffins. With the banning of chlorinated waxes in Germany and Canada, and the requirement of placing warning labels on drums of these materials in this country, alternative lubricant additives are being sought.
While many in the metalworking industry have switched to chlorinated olefins and polyesters, there is a concern among some that these chlorinated products as well may have carcinogenic properties. Hence, non-chlorinated substitutes are considered desirable. While sulfonated products have been satisfactory for light machining applications, they have not been generally satisfactory for heavier machining, such as the severe metal cuts and draws for which the chlorinated paraffins have been favored.
In the past, a number of non-chlorine containing additives have been developed to provide lubricating oil compositions with enhanced friction characteristics for use in engine and machinery lubricating oils and fuels. Such additives have included phosphorous compounds such as metal phosphonates, alkali metal salts of alkylphosphonic acids, and dihydrocarbyl hydrocarbylphosphonates; amines, such as alkoxylated amines; and certain boron-containing compounds. Examples of these prior art lubricating oil additives are discussed, for example, at column 1 of U.S. Pat. No. 4,529,528.
Published European Patent Application No. 152,677 of Lubrizol discloses borated alkoxylated amines as thickeners for water based functional fluids. Borated alkoxylated amines are also disclosed in U.S. Pats. No. 4,400,284; 4,427,560; 4,490,265; 4,533,480 and 4,557,843 of Union Oil Company as intermediates for extreme pressure, anti-wear additives in lubricating compositions.
A series of additives has also been developed by Mobil Oil Corporation which are reaction products (essentially mixtures of simple and complex esters) of organic amines and organic phosphonates or phosphites. Early examples of such compositions are disclosed in U.S. Pat. No. 3,553,131 of Hepplewhite, et al., in which C.sub.6 -C.sub.40 diaryl phosphonates (phosphites) are reacted with primary, secondary, or tertiary organic amines to produce products or mixtures which are incorporated in ester lubricants which are alleged to have higher load-carrying properties, surprising stability under storage and are relatively non-corrosive to metals.
A more recent series of patents of Horodysky, et al., assigned to Mobil, has disclosed engine lubricant and fuel additives which are the reaction product of a phosphorous compound, particularly a C.sub.1 -C.sub.6 dihydrocarbyl phosphite, with an alkoxylated amine or a vicinal diol, with or without a boron compound, such as boric oxide, a metaborate, boric acid, or an alkyl borate. See, for example, U.S. Pats. No. 4,529,528; 4,557,845; 4,557,844; 4,555,353; 4,532,057 and 4,522,629. Mobil U.S. Pat. No. 4,587,026 also discloses borated N,N-bis(2-hydroxypropyl)cocamine in the presence of dodecyl phenol sulfide to give a friction-reducing, high temperature stabilizing additive.
While the reaction products of Heppelwhite and Horodysky, et al. are disclosed as possible additives for use with engine lubricating oils or greases, and as additives to liquid fuels such as gasoline, fuel oil and diesel oil, there is no disclosure of using these compounds for the severe requirements of metalworking fluid additives. Moreover, tests by the present inventors of several of the Horodysky, et al. products have shown serious disadvantages to the use of such products as additives to metalworking fluids, particularly in extreme pressure (EP) applications.